High swirl very low pollution piston engine employing optimizable vorticity metering

Abstract

Method and apparatus for producing intense, consistent swirl and air-fuel-E.G.R.-vorticity charge uniformity without any net penalty in engine power, volumetric efficiency, or pumping work. Method and apparatus permit optimal swirl and turbulence for flame stability and fuel economy throughout the R.P.M.-load phase space of engine operation. Method and apparatus require no substantial changes in combustion chamber shape or basic engine structure. For spark fired engines, the method and apparatus permits operation at air-fuel-E.G.R.-intake manifold vacuum combinations having excellent fuel consumption characteristics combined with very low emissions of CO, HC, and NO. For diesel engines, the method and apparatus permits optimized swirl without the volumetric efficiency and pumping work penalties accepted with present art swirl inducing techniques.

What is claimed is: 
     
       1. In a multicylinder four stroke engine having an exhaust passage and a common intake manifold passage volume for several cylinders with depending intake ports wherein said intake manifold passage volume is maintained below atmospheric pressure during low power operation of said engine wherein said engine has in each intake port a variable restriction adapted to close off at least 70% of each port's flow cross section wherein for each such port the restriction is configured so that flow past it will form a wall attached stream and a step-up protrusion intake manifold passage wall to break up any wall attached backflowing stream of exhaust backflow past said restriction so that said exhaust backflow does not penetrate deeply enough into said manifold passage to disrupt the even delivery of air, exhaust gases, and fuel to the individual cylinders of said engine. 
     
     
       2. A method for achieving stable and rapid dilute combustion to produce very low NO x  output in a piston type engine, wherein the engine includes an engine head, an air throttle, fuel input means, intake volume in an intake manifold fluidly connected between said air throttle and an intake port in the engine head, said head being mounted on a cylinder block including a cylindrical passage in which a piston reciprocates, so that the geometrical combination of said head and said cylinder and said piston form a combustion chamber having a volume of cyclicly varying displacement, said intake porting being connected to the combustion chamber,   a variable restriction element to variably restrict flow in the intake part,   intake valve means opening and closing fluid connection between said intake port and the combustion chamber in phase relation to the piston reciprocations to control flow from the intake port to the combustion chamber,   exhaust valve means fluidly connecting the combustion chamber to an exhaust passage and opening and closing in specific phase relation to piston reciprocation,   ignition means for the combustion chamber firing in phase to piston reciprocation,   said engine operating on the four cycle principle comprising an intake stroke, a compression stroke, a power stroke and an exhaust stroke;   said method comprising the steps of: (1) Producing a dilute combustible air-fuel mixture;   (2) Variably restricting flow of the dilute combustible air-fuel mixture in the intake port to form a "Coanda" wall attached flow and filling the space not occupied by said wall attached "Coanda" flow with a fluid mechanically stable recirculating vortex system, said vortex system smoothly intersecting with said wall attached flow thereby minimizing the turbulent dissipation of the wall attached flow;   (3) Introducing said flow into the combustion chamber through said intake valve opening in the form of a high velocity flow having high angular momentum with respect to the central axis of said cylindrical passage, where the flow pattern through said intake valve opening forms a flow pattern inside said combustion chamber which pattern has the high velocity gradients characteristic of an irrotational vortex;   (4) Controlling the mixture velocity through said intake valve opening so that said velocity may vary over a substantial range for a set engine speed, thereby producing in each combustion chamber a high velocity gradient structured turbulent flow having a flow pattern such that any fluid element located out of combustion chamber boundary layers is by the end of the compression stroke stretched, distorted and spread within the combustion chamber volume so that said fluid element is widely distributed spatially over said combustion chamber volume prior to ignition time, said flow pattern in the combustion chamber substantially increasing fuel concentration gradients so as to produce substantially homogeneous microscale air-fuel-products of previous combustion volume statistics thereby providing low cyclic time losses for mechanically efficient engine operation with very dilute mixtures.     
     
     
       3. A method for achieving stable and rapid dilute combustion to produce very low NO x  output in a piston type engine, wherein the engine includes an engine head, an air throttle, fuel input means, intake volume in an intake manifold fluidly connected between said air throttle and an intake port in the engine head, said head being mounted on a cylinder block including a cylindrical passage in which a piston reciprocates, so that the geometrical combination of said head and said cylinder and said piston form a combustion chamber having a volume of cyclicly varying displacement, said intake porting being connected to the combustion chamber,   a variable restriction element to variably restrict flow in the intake part,   intake valve means opening and closing fluid connection between said intake port and the combustion chamber in phase relation to the piston reciprocations to control flow from the intake port to the combustion chamber,   exhaust valve means fluidly connecting the combustion chamber to an exhaust passage and opening and closing in specific phase relation to piston reciprocation,   ignition means for the combustion chamber firing in phase to piston reciprocation,   said engine operating on the four cycle principle comprising an intake stroke, a compression stroke, a power stroke and an exhaust stroke;   said method comprising the steps of: (1) Producing a dilute combustible air-fuel mixture;   (2) Variably restricting flow of the dilute combustible air-fuel mixture in the intake port to form a "Coanda" wall attached flow and filling the space not occupied by said wall attached "Coanda" flow with a fluid mechanically stable recirculating vortex system, said vortex system smoothly intersecting with said wall attached flow thereby minimizing the turbulent dissipation of the wall attached flow;   (3) Introducing said flow into the combustion chamber through said intake valve opening in the form of a high velocity flow having high angular momentum with respect to the central axis of said cylindrical passage, where the flow pattern through said intake valve opening forms a flow pattern inside said combustion chamber which pattern has the high velocity gradients characteristic of an irrotational vortex so as to produce substantially homogeneous microscale air-fuel-products of previous combustion volume statistics thereby providing low cyclic time losses for mechanically efficient engine operation with very dilute mixtures.